From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it
Date: Mon, 21 Dec 2015 23:13:33 +0100 [thread overview]
Message-ID: <201512212313.34114.arnd@arndb.de> (raw)
In-Reply-To: <4753CD2F-914D-44D5-BD18-8DF94068315D@theobroma-systems.com>
On Monday 21 December 2015, Dr. Philipp Tomsich wrote:
>
> > On 18 Dec 2015, at 13:47, Arnd Bergmann <arnd@arndb•de> wrote:
> >
> >> 3. Follow the PCS up to glibc but always pass syscall arguments in W
> >> registers, like AArch32 compat support (the least preferred option,
> >> the only advantage is a single wrapper for all syscalls but it would
> >> be doing unnecessary zeroing even for syscalls where it isn't needed)
> >
> > This would mean we cannot pass 64-bit arguments in registers, right?
>
> Note that there?s no 32bit registers (the ?w?-form always refers to the lower
> 32bits of a 64bit register, with implicit zero-extension)? and load/store
> instructions always use the full base-register (?x?-form) for address calculation.
> I.e. a load/store would inadvertently pickup ?random garbage? in the upper
> 32bits, if no explicit zero-extension is applied.
>
> In other words: all zero-extensions for 32bit arguments should be explicit
> on the kernel side.
I think that is what Catalin meant with the single wrapper in the description:
the kernel always zeroes out the upper 32 bits in the initial trap, and then
we only need to do sign-extensions for the few cases that need it, and pass 64-bit
arguments in two lower halves. In contrast, approach 1 adds a separate wrapper
for each syscall that takes care of both sign-extending where necessary and
zero-extending all othe 32-bit arguments but not the 64-bit arguments.
Arnd
next prev parent reply other threads:[~2015-12-21 22:13 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-15 21:42 [RFC3 PATCH v6 00/20] ILP32 for ARM64 Yury Norov
2015-12-15 21:42 ` [PATCH v6 01/20] arm64: ilp32: add documentation on the ILP32 ABI " Yury Norov
2015-12-15 21:42 ` [PATCH v6 02/20] arm64: ensure the kernel is compiled for LP64 Yury Norov
2015-12-15 21:42 ` [PATCH v6 03/20] arm64: rename COMPAT to AARCH32_EL0 in Kconfig Yury Norov
2015-12-17 11:23 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Yury Norov
2015-12-23 14:15 ` Yury Norov
2015-12-28 8:43 ` > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile Bamvor Jian Zhang
2015-12-28 9:01 ` [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Zhangjian (Bamvor)
2015-12-29 12:27 ` Yury Norov
2015-12-29 14:59 ` [PATCH] arm64: compat: fix wrong dependency Bamvor Jian Zhang
2015-12-29 13:12 ` [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Yury Norov
2015-12-15 21:42 ` [PATCH v6 05/20] arm64:uapi: set __BITS_PER_LONG correctly for ILP32 and LP64 Yury Norov
2015-12-15 21:42 ` [PATCH v6 06/20] thread: move thread bits accessors to separated file Yury Norov
2015-12-15 21:42 ` [PATCH v6 07/20] arm64: introduce is_a32_task and is_a32_thread (for AArch32 compat) Yury Norov
2015-12-17 11:38 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 08/20] arm64: ilp32: add is_ilp32_compat_{task, thread} and TIF_32BIT_AARCH64 Yury Norov
2015-12-17 11:41 ` Catalin Marinas
2015-12-18 14:11 ` Yury Norov
2015-12-18 14:44 ` Yury Norov
2015-12-21 17:42 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Yury Norov
2015-12-16 15:54 ` Arnd Bergmann
2015-12-16 16:58 ` Catalin Marinas
2015-12-16 17:19 ` Catalin Marinas
2015-12-16 19:17 ` Arnd Bergmann
2015-12-17 10:54 ` Catalin Marinas
2015-12-17 13:56 ` Arnd Bergmann
2015-12-15 21:42 ` [PATCH v6 10/20] arm64:ilp32 use the native LP64 'start_thread' for ILP32 threads Yury Norov
2015-12-16 15:50 ` Arnd Bergmann
2015-12-18 13:57 ` Yury Norov
2015-12-15 21:42 ` [PATCH v6 11/20] arm64:ilp32: support core dump generation for ILP32 Yury Norov
2015-12-17 14:05 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Yury Norov
2015-12-16 16:07 ` Arnd Bergmann
2015-12-17 18:27 ` Catalin Marinas
2015-12-17 20:10 ` Arnd Bergmann
2015-12-17 20:14 ` Andrew Pinski
2015-12-17 20:50 ` Arnd Bergmann
2016-01-05 15:26 ` Yury Norov
2016-01-05 21:12 ` Arnd Bergmann
2016-01-06 17:10 ` Catalin Marinas
2016-01-07 14:13 ` Arnd Bergmann
2016-01-07 15:42 ` Yury Norov
2016-01-07 17:23 ` Catalin Marinas
2015-12-18 11:42 ` Catalin Marinas
2015-12-18 12:47 ` Arnd Bergmann
2015-12-21 18:31 ` Catalin Marinas
2015-12-21 22:19 ` Arnd Bergmann
2015-12-21 18:39 ` Dr. Philipp Tomsich
2015-12-21 22:13 ` Arnd Bergmann [this message]
2015-12-21 22:31 ` Arnd Bergmann
2015-12-23 18:31 ` Yury Norov
2015-12-23 21:48 ` Arnd Bergmann
2015-12-15 21:42 ` [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32 Yury Norov
2015-12-17 14:38 ` Andreas Schwab
2015-12-18 13:49 ` Yury Norov
2015-12-22 12:25 ` Catalin Marinas
2015-12-22 21:44 ` Arnd Bergmann
2015-12-23 13:37 ` Catalin Marinas
2015-12-23 20:41 ` Arnd Bergmann
2015-12-30 17:29 ` Yury Norov
2015-12-30 22:36 ` Arnd Bergmann
2015-12-23 4:21 ` Yury Norov
2015-12-15 21:42 ` [PATCH v6 14/20] arm64: signal: wrap struct ucontext, fp and lr with struct sigframe Yury Norov
2015-12-15 21:42 ` [PATCH v6 15/20] arm64: signal: move ilp32 and lp64 common code to separated file Yury Norov
2015-12-16 16:08 ` Arnd Bergmann
2015-12-18 13:48 ` Yury Norov
2015-12-18 14:09 ` Arnd Bergmann
2015-12-22 17:11 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 16/20] arm64: signal32: move ilp32 and aarch32 " Yury Norov
2015-12-22 14:29 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 17/20] arm64: ilp32: introduce ilp32-specific handlers for sigframe Yury Norov
2015-12-22 17:08 ` Catalin Marinas
2015-12-15 21:42 ` [PATCH v6 18/20] arm64:ilp32: add vdso-ilp32 and use for signal return Yury Norov
2015-12-15 21:42 ` [PATCH v6 19/20] arm64:ilp32: change COMPAT_ELF_PLATFORM to report a a subplatform for ILP32 Yury Norov
2015-12-15 21:42 ` [PATCH v6 20/20] arm64:ilp32: add ARM64_ILP32 to Kconfig Yury Norov
2015-12-16 16:24 ` [RFC3 PATCH v6 00/20] ILP32 for ARM64 Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=201512212313.34114.arnd@arndb.de \
--to=arnd@arndb$(echo .)de \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox